Manufacture of wire coils



NOV- 12, 1963 1. M. soBlEAJsKl 3,110,098

MANUFACTURE 0F WIRE COILS Filed Nov. 25, 1960 lL -lU a ll u Alllrnnllllrlrllnln GEA/fm l l r 1 l-lllml] 5/ l i ul ATTORNEY United States Patent O1 3,110,098 MANUFACTURE F WlRE COILS Isabelle M. Sobieraiski, St. Marys, Pa., assigner to Syl- Vania Electric Products, Inc., a corporation of Delaware Filed Nov. 25, 1960, Ser. No. 71,730 4 Claims. (Cl. 29-423) This invention relates to the manufacture of ne coiled wires such as are used as heaters in electron tubes or laments in incandescent lamps.

In the process of making heaters for electron discharge devices, it is common practice to wind the -heater on a mandrel to form a Wire coil and then to coat the coil with insulating material. When the wire is heavy enough to permit, the coil winding mandrel is removed mechanically before coating. When the coil wire used is too fine to support its own weight, mechanical removal of the mandrel is not practical and the procedure has been to coat the heater while the mandrel is still inside the coil followed by sinte-ring of the coating, and then selectively dissolving the coil supporting mandrel by the use of acids, thus leaving only the coated heater coil. Similarly, where a coiled coil of wire of the type often used Aas a filament for a lamp has been manufactured, it has been the practice to coil the filament about a mandrel, coil the coiled Wire and mandrel into a spiral, cut off sections of the spiral so as to form segments, drop the coil of segments into a vat and dissolve out the mandrel. In both of these instances, the metal of the mandrel and yof the Wire coiled about the mandrel was chosen to be selective -to the action of the acid bath so that only the mandrel would be dissolved out. For example, the mandrel may be molybdenum; the wire coiled about the mandrel may be tungsten and the acid bath may consist of 40 parts concentrated sulphuric acid, a like proportion of concentrated nitric acid and twenty parts of water.

Where very fine wire heaters are so manufactured, that is, Iwhere the cut off segments or sections of spiral are dropped into a common acid vat, it has been found that the coils become entangled, and attempts to separate the coils after mandrel removal result in destruction of the coating on the heaters or permanent deformation of the coils, with resultant loss of manufactured products.

lt is, therefore, an object of this invention to avoid entanglement of the very ne wire coils during the mandrel dissolving operation.

yln carrying out this invention, the segments of coiled eaters or filaments, as they are severed from the spiral or string, drop into vials, one for each heater. The vials are of a size which comfortably erect-1y accommodate the individual heaters or filaments. Within the vials is the acid mixture for dissolving out the mandrel. After the mandrel has been removed, the acid in the vials is replaced by clear Water to wash the segments constituting the heater or filament.

ln order to give a clearer understanding of the invention, attention is directed to the following description and accompanying drawings in which:

FlGS. l and 2, in diagrammatic form, illustrate apparatus for carrying out the process;

FIG. 3 illustrates, in diagrammatic form, an automatic apparatus for carrying out the process; and

FlG. 4 illustrates a plan view of a compartmented tray with coil segments in some `of the compartments.

Referring to FIGS. 1 and 2, after the Wire and mandrel have been coiled into a string 10, in conventional fashion, the segment of filament or heater 12 and lmandrel 13 is cut off from the string by cutting knives 14 and 16 and allowed to drop into a vial or glass tube 18. This vial is provided with a hole in or immediately above the bottom of the vial so as to permit free -transfer of liquids `as the level of lthe acid in the vat.

3,110,098 Patented Nov. 12, 1963 ice therethrough. The hole 20, is, of course, small compared to the diameter of the segment to prevent the segment from falling out of the vial and it is placed close to the bottom or in the bottom to allow proper draining of uids from the vial and to prevent the coil segment :from snugging near the upper end of the vial.

As each vial 18 is loaded with a coil segment 12 and mandrel- 13, it is inser-ted into a beaker or vat 22 preferably provided lwith a ldrain valve 24 and valve controlled inlet pipes 26 and 28 for the admission of acid or rinse water 4to lthe vat, as desired. The vat or beaker 22 is initially filled with taci-d 23 which enters the individual vials 18, after they have been placed in the vat, through the `openings 20 and lling the vials `to the same level The acid then acts, selectively, to dissolve out the mandrel 113, thereby leaving the tine coil of wire intact, self supporting, and without entanglement with adjacent coils.

After the acid dissolving action has been completed, the vat is `drained `and the acid is replaced by clear water. If desired, a hose or hoses may be attached to the water pipe and lead directly into the vials 1S to facilitate the washing operation. If hoses are not used, las many fillings and emptyings of the vat may be employed as desired.

The segment l2 may be formed from tungsten and mandrel 13 may be molybdenum while the acid bath may comprise the nitric and sulphuric acid solution mentioned above. Segments 12 can be coated with an insulating coating before or after removal `of mandrel 13, as desired.

ln FIG. 3 there -is rdiagrammatically shown an automatic mechanism for loading the vials with segments, such as individual heaters. An electric motor 30 drives a Geneva ldrive 32 -to periodically rotate ya shaft 34 yone revolution for each output operation of the gearing in the Geneva drive mechanism. The shaft, through suitable speed reducing gearing 36, 38, drives a shaft 40 mounted for rotation in Xed bearings 42 and 44 and having a split lower end 46 Ito straddle the upper keyed end 4S of a shaft 50. The shaft 50 serves as part of a vial holder y49 of acid resistant material. The holder comprises the shaft S0 rand two circular discs 52 and S4 fastened to the shaft. The upper circular disc 52 is fairly thick and provided with equally Vspaced openings therethrough near the periphery of the disc to snugly and slidably accommodate the vials so that the vials may remain upright in the holder and rest `on .the lower disc. To maintain 4the holder in ydriving engagement with the shaft 40, the shaft 40 is provided -with ears 60 straddling a lever 62 pivoted between `the ears and having lan inturned end 64 engaging a circular rgroove 66 in the upper Iend of shaft Si). A spring 68, seated in recesses in the shaft 40 and lever 62, serves to maintain the end `64 of the lever in engagement with the groove.

The shaft 34 also drives two drum cams 70 and 72 fastened on the shaft, the cams each driving a lever 74 pivoted on a suitable fixed support 76, the free end of the lever driving a slide 7S carrying a knive 80 and slidable in a fixed way 82.

For each lrotation of the shaft, the holder 49' will be indexed one step from Iwhere one vial is beneath the coil string to where the next vial is so located. Also yfor each index of the holder, the knives will be brought together to sever a segment from the string and the segment will drop into the vial, the drum cams being so contoured as to effect a severing action on the string after the holder has been brought to rest.

When the vials in holder 49 have all been filled, the drive to the shaft 34 is discontinued and the lever 62 is manipulated to release the holder. Thereupon the holder with the vials therein is inserted into a vat for acid and rinse treatments of the coil segments 12. while a re- Y 3 placement holder, loaded with empty vials, is attached to the shaft 49.

After the coils have 'been freed `of `acid and properly Washed, they may be dumped from each rvial into an individual compartment Sil-in a tray 82, ready for subsequent handling.

Although one embodiment of the invention has been shown and described, it -Will be apparent to vthose skilled in the art that various changes and modifications may be 'made therein Without departing from the scope of the invention as defined by the appended claims.

What is claimed is:

1. In the method of manufacture of a coil of wire from a string of coiled wire provided with a coil supporting mandrel therein and which mandrel is soluble in acid, while the Wire is not, the steps comprising cutting the string into individual coiled Wire segments, `depositing each segment as it is cut into a perforated container whose bot-tom supports the segment, one segment for each container, placing all of said containers in a common vat lled with an acid to dissolve the mandrel only, and subsequently washing the acid from the mandrelless segments. Y

2. In the method of manufacture of a coil of wire from a string of coiled Wire provided With a coil supporting mandrel therein and which mandrel is soluble in an acid bath While the Wire is not so soluble, the steps cornprising cutting the string into individual coiled Wire segments, depositing each segment as it is out into a container Ihaving a perforation in the side Wall thereof adjacent the bottom thereof, one segment for each container, placing all of said containers in a common vat lled with yan acid to dissolve the mandrel only, and subsequently Washing the acid from the mandrelless segments. Y

one segment for each container, placing all of said conv tainers in a common vat filled with lan `acid to dissolve the mandrel only, and subsequently washing the acid from the mandrelless segments.

4. In the method of manufacture of a coil of wire fromV a string of coiled tungsten provided with a coil supporting mandrel of molybdenum therein and which mandrel is soluble in an acid bath yand consisting essentially :of 40% concentrated sulphur-ic acid, 40% concentrated nitric acid and 20% of Water, while the Wire is not, the steps comprising cutting the string into individual coiled Wire segments, depositing each segment as it is cut into a perforated container whose bottom supports the segment, one segment for each container, placing `all of said containers in a common vat filled with an acid to dissolve the mandl'el only, and subsequently Washing the acid from the mandrelless segments.

References Cited in the le of this patent UNITED STATES PATENTS haar wenn 

1. IN THE METHOD OF MANUFACTURE OF A COIL OF WIRE FROM A STRING OF COILED WIRE PROVIDED WITH A COIL SUPPORTING MANDREL THEREIN AND WHICH MANDREL IS SOLUBLE IN ACID, WHILE THE WIRE IS NOT, THE STEPS COMPRISING CUTTING THE STRING INTO INDIVIDUAL COILED WIRE SEGMENTS, DEPOSITING EACH SEGMENT AS IT IS CUT INTO A PERFORATED CONTAINER WHOSE BOTTOM SUPPORTS THE SEGMENT, ONE SEGMENT FOR EACH CONTAINER, PLACING ALL OF SAID CONTAINERS IN A COMMON VAT FILLED WITH AN ACID TO DISSOLVE THE MANDREL ONLY, AND SUBSEQUENTLY WASHING THE ACID FROM THE MANDRELLESS SEGMENTS. 